Images #1,2 and 3

Findings: Image #1 is a sagittal T1 weighted MR image of the pelvis which demonstrates a well-encapsulated 4 x 4 centimeter mass composed primarily of increased signal located just superior to the right aspect of the uterus. Image #2 is a T1 weighted axial image through the same region demonstrating the mass to be predominantly bright signal with a central focal region of decreased signal, which may represent calcification. Image #3 fat suppressed T1 weighted post contrast enhanced image through the same plane as image #2. The signal "drops out" consistent with the mass being composed of lipid material. There is no evidence for enhancement.

Diagnosis: Ovarian dermoid.

Discussion: Ovarian dermoids (or mature cystic teratomas) are benign lesions composed of mature epithelial elements such as skin, hair, desquamated epithelium, and teeth. Although these masses do not contain fat, they do contain sebum which, being a lipid material, demonstrates signal characteristics identical to fat. Almost all ovarian dermoids contain this lipid material which allows it to be confidently differentiated from other adnexal masses with MR imaging. Specifically, fat saturation techniques can be utilized to unequivocally demonstrate the dermoids predominant lipid component. With ultrasound, these lesions most often are characteristic by a smooth-walled, unilocular cystic structure with a strongly echogenic internal pattern due to the high lipid content. A fat-fluid layer is occasionally seen. Although the majority of ovarian dermoids are asymptomatic, they may present with ovarian torsion.

References:

1. Outwater EK. Imaging of the Voary and Adnexa: Clinical Issues and
   Applications of MR Imaging. Radiology 1995; 194:1-18.

2. Sutton D. Textbook of Radiology and Imaging, 6th Edition. Churchill Livingston.
   New York; 1998:1241-1242, 1260.

3. Kurtz AB. Ultrasound: The Requisites. Mosby, St. Louis; 1996:400-403.